Amplification et émission paramétriques à l'échelle subpicoseconde dans un cristal organique : - application à la spectroscopie infra-rouge

Abstract

High peak power subpicosecond optical pulses have been generated by parametric amplification of a white femtosecond continuum in a new organic crystal, N-(4-nitrophenyl)-L-prolinol (NPP). The relation between this observation and the structural properties, both at microscopic and macroscopic levels of NPP are exposed. Special emphasis is put on the renewal of the traditional concept of non-critical phase-matching in view of the present requirements linked to the observation of ultrafast subpicosecond nonlinear phenomena. The notions of θ-non critical and λ-non critical phase-matching together with their implications are exposed. A new method for time-resolved luminescence spectroscopy with subpicosecond resolution is simply derived as an extension of the NPP nonlinear measurement set-up where a previously used infra-red emitting continuum water cell is simply replaced by any sample of interest with luminescence in the 1.0-1.6 μm range. This new technique, defined as PASS, a tag for Parametric Amplification and Sampling Spectroscopy, is demonstrated at 1.44 μm in a InGaAs-InAlAs multiple quantum well structure. The future of nonlinear organic materials in infra-red optical signal processing systems is briefly discussed in conclusion Impulsions optiques de forte puissance crete obtenues par amplification parametrique d'un continuum de lumiere blanche dans le N-(4-nitrophenyl)-(L)-prolinol) ou NPP. Proprietes du NPP. Revision du concept «accord de phase non critique». Concept «d'accord de phase λ- non critique». Presentation d'une nouvelle methode spectroscopique autorisant une resolution temporelle inferieure a la picoseconde, methode «PASS» pour «Parametric Amplication and Sampling Spectroscopy». Application de PASS a l'etude d'une structure de type puits quantiques multiples